Derivative of the adduct of levopimaric acid and maleic anhydride and method of preparation thereof



Patented Aug. 24, 1948 Dmmwma THE ADDUGT .ol'a Levee- PIMARIC Aomt nNn MALEIQANHXDRIDE a mammalian O-F PREPARATIOMTHEREOF George C: Harris; Wilmington; Dela, assignor to Hereules-Powder Gompanyg: Wilmington- Del. a corporatious-ofiDelaware No Drawinm. Amllication Mg a SerialgNo. 667;496--= This invention relates to" addition products and tea method for their production, and more specifically" it relates "to Diels-Alder addition products of a'resin acid and armonoalkyiester of "fumaric acid" and to. a "method" for the-pro ductionthereof It" is known to produce synthetic resins using as the "starting material "the essentially" pure Diels -Alder addition product of ievo-pimaric' acid and maleic anhydrid'e; Thus, in" U. S: Patent 2,359;98d; Fleck describes the preparation of such an essentiallypure Diels Al'der' addition product, which hedescri'bes as being suitable 'for' use as a startingmateriai "for-the production of highgrade resins 'thatnray be used in varnishes and fdrbtiier"purposes: Suchresins have not been completely satisfactory compositions of matter, however; because they are not stable-when subjectedto. theaction of sunlight, andalso tendto breakidown when-.kettled' with dr'ying oils at the temperatures" enerally employed in varnish manufacture, i. a temperatures of about 250- C; Itis thereforetanob'iect '01" this inventionito prepare'la more usefu1.,additi'o'n product from levo-pimari'c' acid? and" maleic anhydride or maleicacid. It. is; also anobject; of this invention to prepare from l'etvo-pifm'arie acid'fandmaleic anhydride or maleic acid "an addition product which is stable to the action. of sunlight 'and other sources ofultravio'let radiation, and which is also stab-1e when h'eatedat temperatures up to about 250CJS Other objects of this invention are described in the'paragraphs which follow.

The above and other'objects are realized in ac-, cordjance with this invention by-preparinga syn= theti'c material having the structural'formulaiof theDiels-Alder addition product of iev'o-pimari'c a cid and 'a" hmonoester'of 'fumaric acid-and an aliphaticalcohol "having less than fourcarbon atoms." This jaddition'product is? characterized by substantial stability when heated. at250" Q, and" by; substantial resistance to deterioration 140mm. (emcee-10st.

Wliemsubjectedto ultraviolet radiation. De

pending upon, the alC'OhbI employed'in' prep'ar ing'the additioniproduct'ofthis invention, the

sai-diadditibn: product is further characterizedby an acid'num'b'er of 258"-"263"'and amethoxyl con"- tent of 7.1-7.3 75'when'prepared nommethyl-ab coh'ol; by an" acid number of 249 254 and an ethoxyl content of 10.0-10:2%" when prepared from ethyl alcohol; or by an acid number of 2 t1 24e6and apropoxyl -or *isopropoxyl" content of 12:7- -12'3 when" prepared from normal *propyl lcohol or 'isopropyl alcohol; respectively:

Theessential ieature-eithe -method of this inventiomis .the heating .in. solutionrint'tlm; desired aieoholtat: a temperaturetof; 260%25021Gi20f came-.-

terial having the-structuralformula: of DieIs A-Ider addition product-cf. levo-pi'marimaeid-= cedures-- which are well: understood 1 by those skilleddn' the-am Thusvwhem the initial fiddistio'n product of-r levo pimarie': acid andomaleic anhydride is in an essentially pure form: and is characterized by a meltingpoint bythe capil lary- -method of-222228 G5; by an acid number in-acetone-solution of 4-18 426, by-an acid numb irr absolute alcohol solution -of-278283 aud hy alcohor of plus-"25- to -plus- 29, the-resin can-name ventiom may beobtained; after the-dsomerme tibrr step at 200-250- Q; by cooling ,=.the 'minturc and thereafter precipitating the resin by the addition of acid. 0n the other hand," where the i nitial addition product is in an essentiallydmpure form; such as is obtained by the -reection of ordinary' wood rosin and maleic anhydrideat the Tesin- -of- -thisinvention may-be rer covered "after the isomerizat-ion -by removing-the alcohol; dissolvingthe residue in waterand neutralizing theaqueous solution A to 1 aepllwalue of-*'6.0 65"-withan! acid? contactingthe mixture with a suitable water-immisciblesolvent such as benzene; separating the water phase Hom the sol-vent phase, and thereafter adding further acid-'tothe waterphase to precipitate the product of'this-inventi-onr Having thus indicated ina general-' wayithe nature--and-purpose'of this invention, the-iollow in'gexampie is included in order 'to'illustrate the practice thereof.

Example 1 10- g: of the essentially pure Diels Aldervad ditibm product of levo pimaric --acid anet'maleic anhyd'ride imeltingmoint M 221? C. 'bwtheicapfl lary method acid number acetone solution: of 422, acid number-inabsolute alcohol-solution oi 28 1, and falphalg in age-solution in absoluta ethyl alcoh'cl of plus 2'70 was dissolved in Emmi; of hotmethanof; and; the solution made alltallna to phenolphthalein indicator by the addition-r a! precipitate which formed was dissolved in ethyl ether, the solution was washed free of the hydrochloric acid, dried, and the ether evaporated to obtain 10.1 g. (98% yield) of the noncrystalline Diels-Alder addition product of levo-pim'aric acid and the monoester of fumaric acid and methyl.

alcohol. It had an acid number of 260'and a methoxyl content of 7.2%.

temperature of 250 C. this material exhibited remarkable resistance to decomposition, and this material also exhibited substantially greater re- When heated at a I employed, sufiicient alkali metal compound must be present to result in the formation of the disodium, dipotassium, dilithium, etc., salt.

As is shown in the example, it is desirable that the alkaline material be employed in anhydrous form or in relatively concentrated aqueous solution, for example, a solution of 40% or higher, to avoid the addition of a relatively large volume of water to the reaction mixture. Thus, addition of a 5% aqueous sodium,hydroxide solution will cause the precipitation of the disodium salt of the addition product of levo-pimaric acid and the monoester of maleic acid, rendering the method ofthis invention inoperable. The concentrationof: the adduct in the alcohol solution is not so critical, however, and may be varied within a wide range. Hence, the concentration of the levo-pimaric acid-maleic anhydride adduct may sistance to deterioration when subjected to ultraviolet radiation than the initial addition product of levo-pimaric acid and maleic anhydride. The initial addition product which is neutralized and heat treated in alcohol solution may be prepared in accordance with procedures which are well understood by those skilled in the art. Thus, in U. S. Patent 2,039,243, Krzikalla teaches the reaction of ordinary wood rosin and maleic anhydride to yield an impure mixture which is suitable for use as one of the starting materials in accordance with the method of this invention. Particularly advantageous starting materials are those in substantially pure form which consist essentially oithe Diels-Alder addition .product of levo-pimaric acid and maleic anhydride. Such materials are described in U. S. Patent 2,359,980 and also by Fleck and Palkin in vol.

14 of the Analytical Edition of the Industrial and Engineering Chemistry (1942) page 146. In general, any material containingv levo-pimaric acid, or any other resin acid which may be re- .acted with'maleicanhydride to form a material comprising the Diels-Alder addition product of levo-pimaric acid and maleic anhydride may be employedin preparing a starting material useiul in making'the product of this invention. Both the pure and the impure addition products of levo-pimaric acid and maleic anhydride may be prepared from either maleic anhydride or maleic acid,- sinceuse of both of the latter materials will result in the production of identical products as finalresins. In the example, methyl alcohol was used in preparing the product of this invention, but in its place there may be employed any other aliphatic alcoholhaving less than4 carbon atoms,

namely, ethyl alcohol, normal propyl alcohol, and

.-isopropyl alcohol. v Generally speaking, as the alkaline material used in accordance with this invention, I may employ any inorganiccompound of an alkali or alkaline earth metal which is alkaline in aqueous solution and which reacts with the levo-pimaric acid-maleic anhydride adduct to provide a reaction product soluble in water. The alkali metal compounds are preferred since they arecharbewithin the range from 10 to 50% by weight of the solution, the more dilute solutions being preferred for the sake of ease of handling.

In the example, the isomerization was effected at a temperature of 225 C., but any temperature in the range from 200-250 C. may be used. A temperature in the range of 220230 C. is preferred. Furthermore, the period of time during which they isomerization is carried out has been found to be quite critical and should be in the range from about 3 to about 5 hours, preferably 3 in the range of from 4 to 4 'hours. Because of the high temperatures employed, it is necessary that the isomerizationste'p be conducted under superatmospheric pressure, usually from about 4000 to about 6000 lb./sq. in. gage. An inert atmosphere such as hydrogen, nitrogen, etc., is employed in practically achieving the desired reaction conditions.

i As previously stated, the handling of the reaction mixtureupon cooling will depend upon the properties of the initial addition product employed. Where this product is the adduct of levopimaric acid and maleic anhydride in essentially pure form the mixture need be merely neutralized with acid in order to precipitate the product of this invention. Where the initial material is associated with neutralbodies, resinacids and reaction products thereof, in addition to the levopimaric-maleic anhydride adduct, however, such impurities may be separated by removing the alcohol as by distillation, contacting the residue with water, adding acid to the water phase until a pH value of 6.0-6.5 has been attained, contacting the water solution with a suitable water-immiscible solvent, separating the phases, and thereafter adding further acid to the water phase to precipitate the material of this invention. When this procedure is followed, phosphoric, acetic, hydrochloric, sulfuric, or any other organic or inorganic acid, maybe used as the acid precipitating agent. The solvent employed must be water-immiscible and at the same time a solvent for the neutral bodies, resin acids, etc., associated with the levo-pimaric acid-maleic anhydride adduct used as the starting materials. For example, aliphatic hydrocarbons, such as. hexane, petroleum ether, etc.; aromatic hydrocarbons such as benzene, toluene; and ethers such as ethyl ether, etc., may be employed. 7

The addition products prepared in accordanc with this invention are unique and advantageous compositions -of matter. Thus, they and the esters prepared from them are characterized by substantial resistance to deterioration when subjected tothe action of ultraviolet light, in com parison with comparable products of theprior of heat-treatment, heating the said solution at 200-250", C. ina closed vessel for from 3 to 5 hours and recovering the said synthetic material from the reaction mixture.

10. The method for the preparation of a synthetic material having the structural formula of a. product theoretically obtained by Diels-Alder addition of levopimaric and a monoester of fumaric acid with an unsubstituted aliphatic monohydric alcohol having less than four carbon atoms assuming the trans configuration of the fumaric ester group remains unchanged, which method comprises preparing a solution of the DielsAlder addition product of levopimaric acid and maleic anhydride in the said alcohol, adding sufiicient alkalimetal compound to neutralize the solution to the phenolphthalein end point, the said alkali metal compound if employed in aqueous solution being employed in sufiiciently concentrated form such that precipitation is avoided during the subsequent step of heat-treatment, heating the said solution at 200250 C. in a closed vessel for from 3 to 5 hours, cooling the reaction mixture to a temperature below its boiling point, acidifying the reaction mixture to precipitate the said synthetic material and recovering the said synthetic material. I

11. The method for the preparation of a synthetic material having the structural formula of a product theoretically obtained by Diels-Alder addition of levopimaric and the monoester of fumaric acid with methyl alcohol assuming the trans configuration of the fumaric ester group remains unchanged, which method comprises preparing a solution of the Dials-Alder addition product of levopimaric acid and maleic anhydride in' the said alcohol, adding suiiicient alkali metal compound to neutralize the solution to the phenolphthalein end point the said alkali metal compound if employed in aqueous solution being employed in sufiiciently concentrated form such that precipitation is avoided during the subsequent step of heat-treatment, heating the said solution at ZOO-250 C. in a closed vessel for from 3 to 5 hours, cooling the reaction mixture to a temperature below its boiling point, acidifying the reaction mixture to precipitate the'said synthetic material and recovering the said synthetic material. 12. The method for the preparation of a synthetic material having the structural formula of a product theoretically obtained by Dials-Alder addition of levopimaric and the monoester 0f fumaric acid with ethyl alcohol assumin'g'the trans configuration of the fumaric ester group remains unchanged, which method comprises preparing a solution of the Diels-Alder addition product of levopimaric acid and maleic anhydride in the said alcohol, adding suificient alkali metal compound to neutralize the solution to the phenolphthalein end point, thesaid alkali metal compound if employed in aqueous solution being employed in sufliciently concentrated form such that precipitation is avoided during the subse-: quent step of heat-treatment, heating the said solution at 200-250 C. in a closed vessel for from 3 to 5 hours, cooling the reaction mixture. to a temperature below its boiling point, acidifying the reaction mixture to precipitate the said synthetic material and recovering the said synthetic material. v

. 13. The. method for the preparation of a synthetic material having the structural formula of a product theoretically obtained by Diels-Alder addition of levopimaric and the monoester of fumaric acid with isopropyl alcohol assuming the trans configuration of the fumaric ester group remains unchanged, which method comprises preparing a solution of the Dials-Alder addition product of levopimaric acid and maleic anhydride in .the said alcohol, adding suificient alkali metal compound to neutralize the solution to the phenolphthalein end point, the said alkaline material if employed in aqueous solution being employed in sufficiently concentrated form such that precipitation is avoided during the subsequent step of heat-treatment, heating the said solution at 200-250 C. in a closed vessel'for from 3 to 5 hours, cooling the reactionmixture to a temperature below its boiling point, acidifying the reaction mixture to precipitate the said synthetic material and recovering the said synthetic material.

14. The method for the preparation of a synthetic material having the structural formula of a product theoretically obtained by Diels-Alder addition of levopimaric and a monoester of fumaric acid with an unsubstituted aliphatic monohydric alcohol having less than four carbon atoms assuming the trans configuration of the fumaric ester group remains unchanged, which method comprises preparing'a solution in the said alcohol of a material obtained by heattreating rosin with maleic anhydride and containing the Diels-Alder addition product of levopimaric acid and maleic anhydride, adding a sumcient amount of an alkali metal compound to neutralize the solution to the phenolphthalein end point, the said alkali metal compound if employed in aqueous solution being employed in sufficiently concentrated form such that precipitation is avoidedduring the subsequent. step of heat-treatment, heating the said solution at 200-250 C. in a closed vessel for from 4 to 4 /2 hours, removing the unreacted alcohol, acidifying an aqueous solution of .the resulting product to a pH value of 6.0-6.5, contacting the acidified solution with a water-immiscible liquid which is a solvent for the impurities (rosin acids and neutral bodies) contained in the starting material, separating the water phase from the solvent phase, acidifying the water phase to precipitate the said synthetic material and recovering the said synthetic material.

GEORGE C. HARRIS. 

